The objective of the project is to restore a section riverbank where erosion is threatening a formal trail and a buried sanitary sewer pipe. Restoration methods will employ materials and techniques appropriate for the current flow regime.
Toronto and Region Conservation Authority (TRCA) is preparing to restore a section of riverbank along the East Don River in East Don Parkland below Alamosa Drive, located south of Finch Avenue East and west of Leslie Street, in the City of Toronto.
The site was first identified to TRCA by City of Toronto’s Parks, Forestry, and Recreation (PF&R) Division following the August 19th, 2005 storm event which caused extensive erosion to the bank and adjacent asphalt trail, resulting in a risk to public safety. As an interim measure TRCA realigned the asphalt trail away from the erosion scar and planted riparian vegetation in an effort to stabilize the eroding embankment, while developing a long-term solution to address the ongoing erosion, and risk to public safety. In September 2011 TRCA retained Greck and Associates Limited to complete the detailed design for the project.
The development of the final solution to address the ongoing erosion was complicated by the fact that the trail cannot be relocated any further away from the river at this location, as there is an existing 1200 mm sanitary sewer main that runs parallel to the riverbank under the trail, which would potentially be impacted should the river continue to migrate and downcut on its current course, as well as a seasonal wetland located on the opposite side of the trail which offers an important habitat feature within the East Don Parklands. As a result, the proposed restoration works will stabilize the bank in its current location, thereby removing the risk to public safety, providing long-term protection to the existing infrastructure and stabilizing the riverbank while minimizing the potential impact to the wetland area.
Scope of Work
In general, the work involves:
- Construction of a retaining wall, comprised of armourstone with roundstone toe protection, measuring approximately 43 metres in length.
- Installation of vegetated rip rap at both ends of the new retaining wall to mitigate channel outflanking and to provide adequate bed protection for a buried sanitary sewer pipe.
- Removal of a roundstone island and widening and lengthening of pool adjacent to the proposed armourstone retaining wall to alleviate pressure against the new retaining wall and to improve the local flow regime.
- Planting of native trees and shrubs above the new armourstone wall for additional protection against erosion and to improve the diversity of plant species in the vicinity
- Restoration of all disturbed areas with native grasses, shrubs and/or trees as weather conditions permit
Construction Access & Timing
Access will be gained off of Finch Avenue East, just west of Alamosa Drive, where construction equipment will travel southwest along an existing park path to the project site.
In the interest of protecting public safety, temporary fencing and signage will be erected at the site to delineate the limits of the active work area and restrict public access while the work is underway.
Work is scheduled to commence during the week of February 27, 2012 upon the receipt of the necessary approvals and is expected to be completed by March 31, 2012 excluding final site restoration which will be implemented as weather conditions permit.
Public Notices & Contact Information
Project signs will also be erected on Finch Avenue; at the trail entrance to the East Don Parklands, on Alamosa Drive; at the main trail entrance, and in the parklands in at each major trail intersection before the construction area. Contact information where more details about the project, and anticipated trail closure duration can be obtained will be included on the signs.
If you have any questions or comments about the project please contact:
Project Manager, Environmental Engineering Projects
Toronto and Region Conservation Authority
1 Eastville Avenue, Toronto, ON M1M 2N5